Someone who publicly opposes armed conflict in general, or particular conflict, and usually causes conflict in the process.
A derogatory term directed at the bigotry of certain “peace” groups attempting to force their views on society.

Sorry I was late to work today sergeant. Some peacenik group was blocking the gate and antagonizing the Soldiers. I would have liked to express a little of my own ‘free speech’ on them, but instead I just used the other entrance.

Someone who takes the respectable position of non-violence to an absurd degree. Specializes in feel-good, kumbaya messages (bumper sticker slogans) that sound nice but solve nothing. Even when an obvious evil is running amok (Hitler or Stalin), they do little but draw anti-war signs. These kind of people are extremely disdainful of US and Israeli troops, but have little to say about groups like ISIS or hamas.

"I told that peacenik that evil dictators couldn't care less about their signs and rallies."